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ML Aggarwal Solutions Class 10 Mathematics Solutions for Mensuration Exercise 17.4 in Chapter 17 - Mensuration

Question 9 Mensuration Exercise 17.4

A toy is in the form of a cone of radius 3.5 cm mounted on a hemisphere of same radius. If the total height of the toy is 15.5 cm, find the total surface area of the toy.

Answer:

Solution:

The given toy is the combination of cone and hemisphere so we need to add the curved surface area of both to get the total surface area of the toy.

M L Aggarwal - Understanding ICSE Mathematics - Class 10 chapter Mensuration Question 9 Solution image

Given radius of the cone, r = 3.5 cm

Radius of hemisphere, r = 3.5 cm

Total height of the toy = 15.5 cm

Height of the cone = 15.5 – 3.5 = 12 cm

Slant height of the cone, l = √(h2+r2)

l = √(122+3.52)

l = √(144+12.25)

l = √(156.25)

l = 12.5 cm

Total surface area of the toy = curved surface area of cone + curved surface area of the hemisphere

= π rl + 2π r2

= π r(_l+_2r)

= (22/7)×3.5×(12.5+2×3.5)

= (77/7)×(12.5+7)

= 11×19.5

= 214.5 cm2

Hence the total surface area of the toy is 214.5 cm2.

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